Lubricant containing organic sulphides



am-l June 25, 1940 PTEN mosses I oxn'r some oaoamo spurns noun a.Mikeaka and Floyd Laverne Miller,

Elisabeth, N. 3., assignors to Standard 011 Developmenti'lompany, acorporation oi Dela- No mra Application January 23, 1932,

- Serial No. 508,480 I ring in the distillation or destructivedistillation products of petroleum and other natural occurit ringhydrocarbons are especially suitable for the composition and thesemercaptans provide a very convenient and cheap source of combinedsulphides for the composition.

Such sulphur compounds as mixed sulphides, disulphides, trisulphides,tetrasulphides, pentas'ulphides and the like can be manufactured frommixed mercaptans. For example, the pentasulphides can easily be preparedby reacting mercaptans with sulphur monochloride to form the QBtetrasulphides which in turn can be converted into the pentasulphldes byadding the theoretical amount of sulphur and heating to approximately 50C. In general the polysulphides higher than the disulphides, for examplethe I tetrasulphides and pentasulphides are preferred for use in alubricating composition. Other symmetrical or mixed alkyl, aryl, oralkyl aryl sulphur derivatives of this character or thio-ethers areadvantageous for this purpose. 7 35' By way of example only, one methodof preparing polysulphides is one in-which sour gas oil is treated withfree sulphur to yield polysulphides and then distilled under vacuum at atemperature such that the'polysulphides will not distill 40 over, thusobtaining a bottoms containing these sulphur bodies. v As still anotherexample, a method of preparing the .disulphides is described and claimedin the co-pending application No. 537,175 filed. 45 May 13, 1931, ofHerbert G. M.-Fischer in which a spent soda solution used for treatingsour cracked distillates is subjected to a carefully limited treatmentwith oxygen whereby a mixture of disulphides is obtained. In thismethod. 50 a distillate of 90 to 95 ,B'aum, boiling below 300 F., andcontaining 0.18 to 0.3% sulphur, from cracked high sulphur gas oil, istreated with 0.1 to 0.2 volume of a 3 to6% aqueous solution of causticsoda at 80 pounds pressure. The sulgg phur content of the naphtha isreduced by this (or. sr-e) treatment to 0.02 to 0.03%, and the causticsod solution contains a mixture ofmercaptides avera ng about ethylmercaptides in molecular weight. The spent soda solution from the abovetreatment is heated to about 210 F. with steam, 0 and preferably withinthe limits of 100 to 400 F.,

' and without reduction in pressure is thoroughly mixed with a carefullyregulated amount of .oxygen. The amount of oxygen used isdsirablysomewhat less than that required for the com- 1 plate regeneration ofthe caustic soda solution. Under these conditions the reaction proceedsrapidly and smoothly and the oxygen is entirely used up. Other gasmixtures containing oxygen and inert gases may be used such as air, orair w enriched with oxygen, but with such mixtures the reaction rate isslower, and. it is necessary to recover large quantities of thevaporized product from the fixed gases leaving the process. In batchoperation, as in a bomb, it is preferable to supply an excess of oxygen,and about to 40% has been found advantageous.

After the reaction of the spent soda solution with oxygen the resultingmixture is cooled to substantially atmospheric temperature, and ispassed into a relatively large drum where it is permitted to separateinto two layers. The bottom layer consists almost entirely of causticsoda with a very small amount of unconverted mercaptans or other sulphurcompounds, and the upper layer consists almost entirely of disulphldes.The di-sulphide mixture secured in this operation boiled between 275 and340 F., contained 52.3% sulphur by weight, and had a specific gravity of0.982.v These di-sulphides may. be further purified by suitable methodsfor the 1 removal of any residual traces of mercaptans or othercorrosive sulphur compounds.

As a further example an improved method of preparing the thlo-ethers isone in which mercaptans recovered from a similar spent soda solution bysteam distillation are passed in vapor formover catalysts and a productcontainin thio-ethers and hydrogen sulphide is secured.

Polysulphides derived from. mercaptans from.- other sources than naphthatreating also can be used. Similarly polysulphides derived from.mercaptans by other methods than described above are contemplated.

The exact composition of the mixtures ob- 60 tained inthe aboveprocesses for the production of polysulphides and thioethers frompetroleum mercaptans is not known. However, it is unnecessary toseparatethese mixtures into. ultimate pure compounds and a simple fractionation.as naphthas derived to secure mixtures of any desired volatility andboiling range available is sumcient to produce suitable lubricatingcompositions. Pure sul-' phides may be used for this purpose.

By way of example only, a lubricating composition according to theinvention may include mixed pentasulphides and tetrasulphides to. theextent of about 5% by volume and lubricating oil of 50 Saybolt secondsat 210 F. viscosity to the extent of about 95% by volume. The relativepercentages canbe varied as desired and the character ofthepolysulphides and oleaginous material can also be varied.

Other sources of polysulphides are also found to give suitable sulphurbodies for this invention for instance, in refining cracked naphthassuch from sulphur containing crude oils such as West Texas crude, thecracked naphthas are treated with strong sulphuric acid whereby a sludgeis obtained which is high in sulphur content of the nature ofpolysulphides.

The sludge is treated with water to dissolve out the excess sulphuricacid which separates from the oily layer. -The oily layer is thenfurther washed with water after which it is neutralized with sodiumhydroxide or the like to free it from any remaining sulphuric acid.Thethus obtained oily layer contains a high percentage of sulphurcompounds of the nature of polysulphides.

Or, after dissolving the free acid from the sludge with water the acidsolution can be dis: tilled as for example by heating to approximately300 F. under pressure greater than atmospheric with orwithout theaddition of live steam to yield a distillate containing a relativelyhigh percentage of sulphur such as polysulphides. In-

stead of dissolving out the free acid with water the-sludge can bedirectly steam distilled toyield a distillate high in obtained by thesetreatments are high in combined sulphur content and are adapted for usein lubricatingv compositions.

: Petroleum lubricating oil .alone,- or in admixture. with lubricatingvegetable, fish and/or animal oils,. or mixtures of the same, may beused t6 make a product of any desired'speciflc'gravity,

sulphur content, or viscosity ranging from a very mobile' oil to agrease.

Various changes may be made within the scope of the appended claims inwhich it is desired to claim all novelty inherent in the invention asbroadly as the prior art permits. v V We claim: 1. A lubricatingcomposition adapted for extreme pressure, comprising a minerallubricating oil and a small quantity of 'polysulphides derived frommercaptans obtained in the refining of petroleum. I

2.1; lubricating composition adapted for extreme pressure, comprising amineral lubricatly small quantity comprising a hydrocarbon lubricantamount sumcient to give the vmixture increased polysulphides. Thematerials eating oil and about 5% ing oil and a small quantity ofpolysulphides de- 3. A lubricating composition adapted for extremepressure, comprising an oleaginous material having lubricatingproperties and a relativeof organic polysulphide derived from petroleum.

4. A lubricating composition adapted for extreme pressure,'comprising anoleaginous material having lubricating properties and a relatively smallquantity of an organic polysulphide derived from the acid sludgeresulting from the treatment of petroleum hydrocarbons with sulphuricacid.-

5. An extreme pressure lubricant composition comprising a hydrocarbonlubricant and a small amount, suflicient to give the mixture increasedload-bearing capacity, of an alkyl tetrasulphide.

6. A lubricating composition adapted for extreme pressure comprising amineral .lubricating oil and a small quantity of organic polysulphideshaving from 4 to 5 atoms of sulphurper molecule and derived from.petroleum.

7. An extreme pressure lubricant composition comprising a hydrocarbonlubricant and a small amount suflicient to give the mixture increasedload bearing capacity of an organic polysulphide having from 4 to 5sulphur atoms per molecule.

8. An extreme pressure lubricant composition and a small loadbearingcapacityof a hydrocarbon polysulphide having from 3 to 5 atoms ofsulphur per molecule.

9. An extreme pressure lubricant composition comprising ahydrocarbonlubricant and a small amount sufiicient to give the mixtureincreased load bearing capacity of an alkyl pentasulphide.

. 10. A.cutting oil comprising a mineral lubricatingI oil and'a smallamount suilicient to give the mixture increased extreme pressurelubrication characteristics of a hydrocarbon polysulphide jwherein thehydrocarbon groups attached to the sulphur represent the same ordifierent alkyl or arylradicals and the number of sulphur atoms in themolecule is greater than 2.

- 11. A cutting oil according to claim 10in which the number of sulphuratoms per molecule of the said hydrocarbon polysulphide is from 3 to 5.12. A cutting oil comprising a mineral lubriby volume of a hydrocarbon'polysulphide wherein the hydrocarbon groups attached to the sulphurrepresent the same or diflerent alkyl or aryl radicals and the number ofsulphur atoms in the molecule is greater than 2.

13. A cutting oil according to claim 10 in which the said hydrocarbonpolysulphide is an aryl tetrasulphide.

'LOUIS A; MIKESKA.

FLOYD LAVERNE MILLER...

